1. Field of the Invention
The subject invention relates generally to burners used for the combustion of used or waste liquid fuels and more specifically to an improved oil preheater design incorporated into a waste oil burner.
2. Description of Prior Art
Owners of waste oil burners are typically the generators of the waste oil. In North America alone, billions of gallons of petroleum based waste oil are generated annually. Additionally, many more gallons of vegetable based waste oil are generated each year. Both of these types of waste oils are potential fuels for use in a waste oil burner.
By properly combusting these substances, an unwanted or otherwise potentially hazardous substance can provide an economical method of heating. However, despite these benefits many waste oil burner owners have become discouraged with the complexity and frequency of basic routine maintenance services required to maintain the proper operation of current designs.
While numerous patents have been issued for waste oil burners of reasonably good operation, all waste oil burners are known to suffer from a number of disadvantages. Most waste oil burners operate in a similar manner. In order to completely and efficiently burn the waste oil, it must be pre-heated to near combustion temperatures before ignition. The formation of oil carbonization or “sludging” is an unfortunate side effect when heating waste oil to these high temperatures. This carbonization or sludging can partially clog the oil preheating passages and/or the discharge nozzle causing poor operation, or completely plug the passages and/or the discharge nozzle disabling burner operation.
In order for the burner unit to readily ignite upon a demand for heat, most prior art designs incorporate an electrical heater which is energized to keep the preheater block at near combustion temperature, even during standby periods. During normal burner operation the waste oil fuel is constantly flowing while it is being heated. The carbonization or sludging condition is worsened during periods of burner standby when no flow of the waste oil fuel exists, and yet heat is still applied by the preheater assembly. During burner standby periods, the oil contained within the preheater assembly is easily overheated if heat is continually applied. This can result in the oil burning onto the heater element or other heated surfaces increasing the formation of carbonization, and restricting or stopping the flow of oil through the heated passages, which in turn increases the frequency of maintenance services. The longer the oil preheating period is, the greater the amount of oil carbonization formed.
In these prior art designs, oil preheater assemblies are relatively large in size by comparison to the present invention. To reduce oil carbonization in these prior art designs low wattage heaters ranging from 50 to 300 watts are most commonly utilized. As a result, a long warm up period is required. Once warmed up, preheater block temperature must be maintained by keeping the heater element energized in order for the burner to ignite on demand. As a result, large cumulative amounts of electrical energy are consumed over the course of the heating season during standby periods when no heat output from the burner is required. The cost of high-temperature preheating during these standby periods reduces the economic savings potential of a waste oil burner.
Some prior art designs use an external preheater. These designs must be heated more than required for proper combustion due to the cooling of the oil that occurs as it travels from this external heater to the discharge nozzle. This design thereby increases carbonization and electrical operation cost. Some of these designs incorporate an additional heater in the nozzle discharge area further increasing burner manufacturing cost, system complexity, electrical operation cost, and maintenance requirements.
Due to the formation of carbonization, all preheater blocks must be routinely maintained by performing a cleaning procedure. Many prior art designs use multiple oil passages drilled through an aluminum block. When carbonization forms inside of these heated passages, cleaning requires extensive disassembly of components in order to access the preheater block ports with a suitable cleaning tool. Other designs use a cylindrical chamber. One of these designs incorporates an internal spiraling passage. This design is time consuming and difficult to service as it requires the waste oil burner owner or service person to clean carbonization from an internal spiraling passage which is similar in design to the internal threads of a nut for a bolt. Another cylindrical design is housed externally to the burner assembly making it somewhat easier to access than other designs; however a secondary preheater is incorporated prior to the discharge nozzle which also requires maintenance. This dual preheater design increases the manufacturing, maintenance, and operational cost of the burner.
Due to the degree of difficultly, the cleaning and maintenance procedure of oil preheater assemblies has traditionally been performed by a professionally trained service person, or by the manufacturer itself. In other cases the entire preheater assembly is replaced as routine maintenance, rather than servicing existing components further increasing maintenance and operational cost of the burner.
Most prior art preheater units are difficult to remove for service, and all are more difficult and more time consuming to directly access the heated passages or heated surfaces for cleaning than the present invention as the present invention provides an improved method of access to these heated oil passages. Another improvement of the present invention reduces the electrical energy consumption used for preheating the waste oil by turning off all electrical power to the oil preheating circuit during standby periods creating a more economical waste oil burner to operate. As an additional benefit of turning off power to the oil preheating circuit during standby periods, this design improvement also reduces the formation of carbonization caused by the excessive preheating of the waste oil fuel, thereby reducing the frequency of maintenance required creating a more desirable waste oil burner to own and operate.
A low pressure siphoning type of atomizing discharge nozzle is the type most commonly used in waste oil burners. Another improvement of the present invention incorporates a method of cleaning contamination from this type of discharge nozzle by intermittently discharging high pressure compressed air through the low pressure oil circuit of the discharge nozzle. This procedure can be performed by the operator on demand by manually pressing a button. This procedure can also be performed by incorporating an automatic system which would operate at predetermined intervals to maintain a clean nozzle.
The present invention incorporates a simplified design which does not require the time consuming nor complicated disassembly of prior art waste oil burners when performing routine maintenance. This allows the waste oil burner owner to quickly and easily perform the routine maintenance him or herself.
The design of the present invention reduces electrical energy consumption and the formation of carbonization. The present invention utilizes a method of cleaning the low pressure siphoning type of discharge nozzle without the need for component removal or disassembly. As a result, the present invention creates a more desirable waste oil burner to own and operate as prior art designs have a significantly higher cost of ownership than the present invention.
Reference to Bender U.S. Pat. No. 5,067,894 dated Nov. 26, 1991
A slide out preheater block design makes removal of the preheater as an assembly quite fast. However, disassembly of the unit for oil passage cleaning is quite difficult. The slide out preheater block unit incorporates a complex system of wiring and related controls which must be completely disassembled requiring a great deal of system knowledge and time in order to perform routine preheater block maintenance services. The drilled passage preheater block design requires removal of steel plugs which are often seized into the aluminum block. Once the plugs are removed, the drilled passages require a time consuming method of brushing before the reassembly process can be performed.
During the heating season, an electrical heater is energized to keep the preheater block warmed up so that the waste oil burner is ready to ignite upon a demand for heat. The heater is energized even during standby periods, increasing the formation of carbonization and consuming large amounts of electrical energy over the course of the heating season. This design additionally increases carbonization formation because the waste oil comes into direct contact with the surface of the heater element resulting in more frequent nozzle clogs. When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Kagi patent application Ser. No. 10,715,079 dated Dec. 13, 2004
This design incorporates the preheater block as a more integral and structural component of the overall burner unit itself. The preheater block is not easily removed for service and requires disassembly of almost the entire burner assembly including a complex system of wiring and related controls. This requires a great deal of system knowledge and time in order to perform routine preheater block maintenance services.
During standby periods, an “air” heater element contained within the preheater block assembly is always on, consuming large amounts of electrical energy over the course of the heating season. During burner operation this design energizes an additional heater element that is in direct contact with the waste oil. This design increases carbonization formation because the oil comes into direct contact with the surface of the oil heater element resulting in more frequent nozzle clogs. When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Briggs U.S. Pat. No. 5,879,149 dated Mar. 9, 1999
This design uses an external cylindrical style oil preheater with an additional preheater located near the discharge nozzle. Both preheaters require periodic maintenance services. The use of two separate preheater assemblies adds to the complexity and cost of manufacturing, as well as adding to the complexity and time required for routine maintenance services.
Throughout the heating season the external cylindrical preheater is energized, during both operational and standby periods, consuming large amounts of electrical energy over the course of the heating season. Because the oil is heated during standby times when the oil remains in the preheater rather than flowing through it, this design increases carbonization formation resulting in more frequent nozzle clogs. When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Schubach U.S. Pat. No. 4,877,395 dated Oct. 31, 1989
This design uses cylindrical style oil preheater with an internal spiraling oil passage. The preheater assembly is incorporated into the burner assembly as an integral component which is not easily removed for disassembly and service. This type of preheater is also difficult to clean due to the internal spiraling “threaded” style of oil passage design.
Throughout the heating season the preheater is always energized, during both operational and standby periods, consuming large amounts of electrical energy over the course of the heating season. Because the oil is heated during standby times when the oil remains in the preheater rather than flowing through it, this design increases carbonization formation resulting in more frequent nozzle clogs. When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Specht U.S. Pat. No. 5,080,589 dated Jan. 14, 1992
This design uses a dual oil preheater system. A “secondary heater” is energized to maintain oil temperature at or near combustion temperature during standby periods. A “primary heater” is energized during burner ignition periods.
The use of two separate preheater assemblies increases the complexity and cost of manufacturing, as well as adding to the complexity and time required for routine maintenance services.
Throughout the heating season the “secondary” preheater is energized during standby periods, consuming large amounts of electrical energy over the course of the heating season. Because the oil is heated during standby times when the oil remains in the preheater rather than flowing through it, this design increases carbonization formation resulting in more frequent nozzle clogs.
When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Foust U.S. Pat. No. 5,341,832 dated Aug. 30, 1994
During preheating cycles this design incorporates a complex pre-burn and post-burn waste oil fuel circulation and filtering system which increases burner manufacturing cost. It is intended to reduce, but not eliminate, the frequency of preheater block cleaning. This design adds to system complexity and increases the level of difficulty in performing routine maintenance services. Because the oil supply pump operates during the preheating and post-burn cycles this design increases electrical operation cost. While a reduction in the formation of carbonization was achieved the benefit was out-weighed by the additional manufacturing and operational cost.
Disassembly of the unit for oil passage cleaning is quite difficult. The preheater block unit incorporates a complex system of passages, wiring, and related controls which must be disassembled, requiring a great deal of system knowledge and time in order to perform routine preheater block maintenance services. The drilled passage preheater block design requires removal of plugs to access passages for cleaning. Once the plugs are removed, the drilled passages require a time consuming method of brushing before the reassembly process can be performed.
When nozzle clogging occurs access to the nozzle for nozzle removal and cleaning is required.
Reference to Masin U.S. Pat. No. 6,132,203 dated Oct. 17, 2000
Instead of using a low pressure siphoning type of atomizing discharge nozzle, this prior art design uses a specially designed high pressure discharge nozzle with a wire mesh strainer incorporated into the nozzle. A purging air line is incorporated into the high pressure nozzle assembly allowing the strainer to be cleaned by back flushing with air into a separate blowdown tank which then requires draining and or cleaning.
Nozzle contamination and wear is increased in waste oil burning devices due to the heavy metal and other contamination contained within the waste oil fuel. Most manufacturers of waste oil burners use a low pressure siphoning type of atomizing discharge nozzle which offers more resistance to clogging and can pass higher viscosity waste oils, requiring less preheating, due to the larger discharge orifice. A high pressure nozzle uses a smaller discharge orifice than a low pressure siphoning type of nozzle and therefore is more prone to both clogging and nozzle wear requiring more frequent cleaning and/or replacement.
By using a specially designed high pressure nozzle, the cost of manufacturing and maintenance is increased in this prior art design. The smaller discharge orifice of a high pressure nozzle requires a lighter viscosity fuel for proper flow and atomization requiring higher preheating temperatures to further reduce waste oil fuel viscosity than a siphoning type of nozzle. Higher preheater temperatures result in more carbonization forming in the preheater assembly and higher electrical operation cost. The preheater of this prior art design is energized even during standby periods, further increasing the formation of carbonization and consuming large amounts of electrical energy over the course of the heating season.